Global distribution of aerosols over the open ocean as derived from the coastal zone color scanner

Climatological maps of monthly mean aerosol radiance levels derived from th e coastal zone color scanner (CZCS) were constructed for the world's ocean basins. This is the first study to use the 7.5-year CZCS data set to examin e the distribution and seasonality of aerosols over the open ocean on a glo bal scale. Examination of our satellite images found the most prominent lar ge-scale patch of elevated aerosol radiances in each month off the coast of northwest Africa. The well-known, large-scale plumes of elevated aerosol l evels in the Arabian Sea, the northwest Pacific, and off the east coast of North America were also successfully captured. Radiance data were extracted from 13 major open-ocean zones, ranging from the subpolar to equatorial re gions. Results from these extractions revealed the aerosol load in both sub polar and subtropical zones to be higher in the Northern Hemisphere than in the Southern Hemisphere. Aerosol radiances in the subtropics of both hemis pheres were about 2 times higher in summer than in winter. In subpolar regi ons, aerosol radiances in late spring/early summer were almost 3 times that observed in winter. In general, the aerosol signal was higher during the w armer months and lower during the cooler months, irrespective of location. A comparison between our mean monthly aerosol radiance maps with mean month ly chlorophyll maps (also from CZCS) showed similar seasonality between aer osol and chlorophyll levels in the subpolar zones of both hemispheres, i.e. , high levels in summer, low levels in winter. In the subtropics of both he mispheres, however, chlorophyll levels were higher in winter months which c oincided with a depressed aerosol signal. Our results indicate that the nea r-IR channel on ocean color sensors can be used to successfully capture wel l-known, large-scale aerosol plumes on a global scale and that future ocean color sensors may provide a platform for long-term synoptic studies of com bined aerosol-phytoplankton productivity interactions.